[C++26] pack_indexing

Reference:

https://en.cppreference.com/w/cpp/language/pack_indexing

https://godbolt.org/z/9eP8qT64s

#include <type_traits>

template <typename... Ts>
using last_type_t = Ts...[sizeof...(Ts) - 1];
 
template<typename... T>
void run(T... t) {
    decltype(t...[1]) i = 0; // float
}

int main() {
 static_assert(std::is_same_v<last_type_t<int>, int>);
 static_assert(std::is_same_v<last_type_t<bool, char>, char>);
 static_assert(std::is_same_v<last_type_t<float, int, bool*>, bool*>);

 struct tmp{};

 run(1, 2.0f, tmp{});
}